Open Firmware Boot Settings

Given that the machines comprising the cluster must serve for student use as well, we need both policy and methodology to implement smooth sharing of resources.

Furthermore, to make the project fly in the first place, it is best not to hinder in any way the work of the system administrators because we want to run a cluster.

It is essential that our resource sharing leaves them in complete control and does not increase their workload in any way.

(put that in its own file, offtopic ?)

We achieve complete automated control over which OS the G4 machines boot if we apply the following two Open Firmware settings:

	setenv boot-device enet:0,bootme,,,2
	setenv default-gateway-ip 192.168.2.1

Details:

• boot-device

  enet:

  use ethernet device as opposed to hard disk or floppy disk or...

  0

  use DHCP to request an IP address

  ,bootme

  use TFTP to request for a "boot file" named bootme

  ,,,2

  dhcpretries parameter. The default is five, which takes 4 minutes to timeout if the DHCP server is not responding. Using a value of "two", times out after only 30 seconds, and then MacOS is booted by default.

• default-gateway-ip

  192.168.2.1

  IP address of OUR DHCP server "master". This makes OF arp for our DHCP server (hence the need for the kernel arp fix, and only attempt to get an IP address from our DHCP server. NOTE: This has no effect on what DHCP server MacOS will use when it boots, it only affects OF when booting from the network. Thus our DHCP server can peacefully coexist with the existing DHCP server which the MacOS machines have been using.

Next: Forth Boot Script TODO - provide links to information on "boot-device" comma options and usage.